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  • Gas chromatography  (129)
  • Springer  (129)
  • Wiley
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  • 1
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Calix[4]arene-tetramethyldisiloxane stationary phases ; Geometric and positional isomer separations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Poly(p-tert-butyldimethoxydipropyloxycalix[4]arene-tetramethyldisiloxane) (TBCX-TMDS) and poly(dimethoxydipropyloxycalix[4]arene-tetramethyl-disiloxane) (CX-TMDS), have been prepared and used as stationary phases for isothermal capillary gas chromatographic separations of positional isomers. Retention factors and separation factors for the isomers were measured. The isomers investigated were well-resolved on the two phases. Retention of all the solutes investigated is greater on TBCX-TMDS than on CX-TMDS, probably because of extra dispersive interactions of the solutes with thetert-butyl groups of the phase. Separation factors for closely-eluting isomer pairs are similar on the two phases. This seems to indicate either that the solutes are retained by non-inclusion processes or that if the isomer molecules do enter the cavity of the calixarene, i.e. the solute is retained by inclusion, thetert-butyl groups do not play a role in discriminating between the isomers.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Morpholine ; Hydrazine ; Boiler feed water and steam condensates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Hydrazine, an oxygen scavenger in boiler water, was derivatised to the corresponding acetone azine and determined at the ng ml−1 level by gas chromatography. Morpholine, a corrosion inhibitor used in steam boilers, was estimated either directly (if 〉2.0 μg ml−1) or by quantitative preconcentration (0.1 ng – 2.0 μg ml−1). To obtain symmetrical peaks for these amines, the column packing was coated with KOH. Use of a nitrogen-specific detector improved accuracy of estimation of hydrazine and morpholine, giving a RSD of 1.9–3.6%. Chromatographic analysis of these amines in boiler feed water and steam condensate samples collected from boilers servicing a petroleum refinery is described. Environmental safety regulations calls for monitoring of hydrazine and the methods developed can easily be adapted for this purpose.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Packed column separations ; C1−C4 alcohols ; Ethers ; Gasoline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A number of oxygenated compounds such as C1−C4 alcohols, methyl tert-butyl ether (MTBE), and tertamyl methyl ether (TAME) are increasingly being used in gasoline as octane boosters and to reduce vehicular emissions. Monitoring of individual oxygenates in gasoline is important for quality control and regulatory purpose. Although, several analytical methods based on gas chromatography have been reported, a need was still felt to develop a simple and cost effective method of analysis. In this paper, a packed column gas chromatographic method is described for the analysis of C1−C4 alcohols, MTBE and TAME over a wide concentration range (2–20% V/V) in gasoline. The method involves determination of alcohols and ethers separately on two different columns. The alcohols are determined on a 20 ft column packed with poly(ethylene glycol) 400 as a stationary phase while the ethers are analysed on a 20 ft OPN-Poracil C column. The analysis of alcohols on poly(ethylene glycol) 400 column also provides data on aromatic components of gasoline.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 31 (1991), S. 173-176 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Stationary phase optimization ; Mobile phase optimization ; Column temperature optimization ; Multifactor optimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A computer-assisted method is presented for the simultaneous multifactor optimization (stationary phase loading, column temperature and carrier gas flow rate) of the analytical conditions for the optimum separation of multicomponent samples in gas chromatography. The optimization of the separation over the experimental region is based on a special polynomial from twelve preliminary experiments using the resolution as the selection criterion. Computer scanning technique was used for optimum selection in three dimensions. Excellent agreement was obtained between the predicted data and the experimental results.
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  • 5
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Pulsed discharge emission detector ; Emission spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This publication contains our initial development of a pulsed discharge emission detector (PDED) (patent pending). It uses a pulsed high voltage discharge in helium, which provides a stable source for atomic and polyatomic emission spectroscopy. We have evaluated this detector for both quantitative and qualitative analysis of a range of chemical compounds. Emission spectra observed from the pulsed high voltage discharge are valuable for spectral analysis. The results obtained for selected permanent gases in the ultraviolet, visible and infrared regions of the optical spectrum indicate that these spectra can be used for compound identification after a chromatographic separation. The data are unique in our opinion and serve as a basis for the future development and investigation of the analytical significance of this detection method.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 42 (1996), S. 547-550 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Supercritical Fluid Extraction ; Pesticides Residues ; Chlorothalonil ; Appels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new method for the extraction of Chlorothalonil residues from apples using supercritical CO2 as the extracting fluid is described. The supercritical fluid extraction results were compared with those obtained by solid-liquid extraction. The results showed that SFE is faster and more selective with better recovery and higher selectivity.
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  • 7
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Electron capture detection ; Mass spectrometric detection ; Atomic emission detection ; PCBs in marine sediments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Electron capture detection (ECD), low- and highresolution mass spectrometry (LR- and HRMS), and atomic emission detection (AED) were compared for the gas chromatographic (GC) detection of polychlorinated biphenyls (PCBs) present in highly contaminated marine sediments. With ECD, LRMS, and even HRMS, detection was seriously disturbed by the complex matrix of the sediments, whereas AED in the chlorine-selective mode provided excellent PCB profiles without interferences. In addition, GC-AED provided congener independent responses, which enabled accurate quantitation of all PCBs based on a single calibration curve. However, because GC-AED was less sensitive than the other techniques studied, preparation of relatively large amounts of sample (10–20 g dry sediment) was required for most analyses.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Electron-capture ; Thermal-energy electrons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The products resulting from the reaction between thermal energy electrons and organic compounds have been investigated to further our knowledge of the mode of action of the electron-capture detector. Thermal energy electrons were generated by maintaining a corona discharge between a stainless steel cathode and a silver/silver chloride anode. The effects of electrode geometry, gas composition, gas flow rate, and the physical properties of the test substances were investigated. The design of the reactor was modified to minimize losses of unchanged substrate. Reaction products of benzaldehyde, tolualdehydes, chlorobenzaldehydes, and dichlorobenzenes were identified by combined gas chromatography — mass spectrometry.
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  • 9
    ISSN: 1612-1112
    Keywords: Gas chromatography ; (S)-(+)-Naproxen ; Amino acid methyl esters ; Resolution of diasteroisomers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A GC method has been elaborated for the separation of enantiomers of some amino acid methyl esters after derivatization with activated (S)-(+)-naproxen. Nine amino acid ester paris were completely resolvede in a single run on a fused silica capillary column.
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  • 10
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Coke oven gas evolution ; On-line gas analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A gas chromatograph will thermal conductivity detector (TCD) connected on line via a cleaning train to the semi-industrial scale Coke Oven Text Plant of the Spanish National Coal Institute (INCAR), has been used to control the evolution of the permanent gases during the coking process. The undesirable presence of oxygen in the coke oven gas can be detected with this system that will be applied to determine the end of the coking process by quantitative analysis of the gas evolved.
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